/*
silverPDF is sponsored by Aleyant Systems (http://www.aleyant.com)

silverPDF is based on PdfSharp (http://www.pdfsharp.net) and iTextSharp (http://itextsharp.sourceforge.net)

Developers: Ai_boy (aka Oleksii Okhrymenko)

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above information and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR SPONSORS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

*/
#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using System.Globalization;
using System.Text;
using System.IO;
using PdfSharp.Internal;
using PdfSharp.Pdf.Advanced;
using PdfSharp.Pdf.Internal;
using PdfSharp.Pdf.IO;

namespace PdfSharp.Pdf
{
  /// <summary>
  /// Base class of all composite PDF objects.
  /// </summary>
  public abstract class PdfObject : PdfItem
  {
    /// <summary>
    /// Initializes a new instance of the <see cref="PdfObject"/> class.
    /// </summary>
    protected PdfObject()
    { }

    /// <summary>
    /// Initializes a new instance of the <see cref="PdfObject"/> class.
    /// </summary>
    protected PdfObject(PdfDocument document)
    {
      this.Document = document;
    }

    /// <summary>
    /// Initializes a new instance from an existing object. Used for object type transformation.
    /// </summary>
    protected PdfObject(PdfObject obj)
    {
      this.Document = obj.Owner;
      // If the object that was transformed to an instance of a derived class was an indirect object
      // set the value of the reference to this.
      if (obj.iref != null)
        obj.iref.Value = this;
    }

    /// <summary>
    /// Creates a copy of this object. The clone does not belong to a document, i.e. its owner and its iref are null.
    /// </summary>
    public new PdfObject Clone()
    {
      return (PdfObject)Copy();
    }

    /// <summary>
    /// Implements the copy mechanism. Must be overridden in derived classes.
    /// </summary>
    protected override object Copy()
    {
      PdfObject obj = (PdfObject)base.Copy();
      obj.document = null;
      obj.iref = null;
      return obj;
    }

    /// <summary>
    /// Sets the object and generation number
    /// Setting the object identifier makes this object an indirect object, i.e. the object gets
    /// a PdfReference entry in the PdfReferenceTable.
    /// </summary>
    internal void SetObjectID(int objectNumber, int generationNumber)
    {
      PdfObjectID objectID = new PdfObjectID(objectNumber, generationNumber);

      // TODO: check imported
      if (this.iref == null)
        this.iref = this.document.irefTable[objectID];
      if (this.iref == null)
      {
        this.iref = new PdfReference(this);
        this.iref.ObjectID = objectID;
      }
      this.iref.Value = this;
      this.iref.Document = this.document;
    }

    //internal void SetObjectID2(PdfObjectID objectID)
    //{
    //  if (this.iref == null)
    //    this.iref = this.document.irefTable[objectID];
    //  //this.iref = new PdfReference(this);
    //  //this.iref.ObjectID = objectID;
    //  this.iref.Value = this;
    //}

    /// <summary>
    /// Gets the PdfDocument this object belongs to.
    /// </summary>
    public virtual PdfDocument Owner
    {
      get { return this.document; }
    }

    /// <summary>
    /// Gets or sets the PdfDocument this object belongs to.
    /// </summary>
    internal virtual PdfDocument Document
    {
      set
      {
        if (!Object.ReferenceEquals(this.document, value))
        {
          if (this.document != null)
            throw new InvalidOperationException("Cannot change document.");
          this.document = value;
          if (this.iref != null)
            this.iref.Document = value;
        }
      }
    }
    internal PdfDocument document;

    /// <summary>
    /// Indicates whether the object is an indirect object.
    /// </summary>
    internal bool IsIndirect
    {
      // An object is an indirect object if and only if is has an indirect refernece value.
      get { return this.iref != null; }
    }

    /// <summary>
    /// When overridden in a derived class, prepares the object to get saved.
    /// </summary>
    internal virtual void PrepareForSave()
    {
    }

    /// <summary>
    /// Saves the stream position. 2nd Edition.
    /// </summary>
    internal override void WriteObject(PdfWriter writer)
    {
      Debug.Assert(false, "Must not come here!");
      //      Debug.Assert(this.inStreamOffset <= 0);
      //      if (this.inStreamOffset == 0)
      //      {
      //        //this.InStreamOffset = stream.Position;
      //        this.document.xrefTable.AddObject(this);
      //        return Format("{0} {1} obj\n", this.objectID, this.generation);
      //      }
      //      else if (this.inStreamOffset == -1)
      //      {
      //
      //      }
      //      return null;
      //
    }

    /// <summary>
    /// Gets the object identifier. Returns PdfObjectID.Empty for direct objects.
    /// </summary>
    internal PdfObjectID ObjectID
    {
      get { return this.iref != null ? this.iref.ObjectID : PdfObjectID.Empty; }
    }

    /// <summary>
    /// Gets the object number.
    /// </summary>
    internal int ObjectNumber
    {
      get { return this.ObjectID.ObjectNumber; }
    }

    /// <summary>
    /// Gets the generation number.
    /// </summary>
    internal int GenerationNumber
    {
      get { return this.ObjectID.GenerationNumber; }
    }

    ///// <summary>
    ///// Creates a deep copy of the specified value and its transitive closure and adds the
    ///// new objects to the specified owner document.
    ///// </summary>
    /// <param name="owner">The document that ownes the cloned objects.</param>
    /// <param name="externalObject">The root object to be cloned.</param>
    /// <returns>The clone of the root object</returns>
    internal static PdfObject DeepCopyClosure(PdfDocument owner, PdfObject externalObject)
    {
      // Get transitive closure
      PdfObject[] elements = externalObject.Owner.Internals.GetClosure(externalObject);
      int count = elements.Length;
#if DEBUG_
        for (int idx = 0; idx < count; idx++)
        {
          Debug.Assert(elements[idx].XRef != null);
          Debug.Assert(elements[idx].XRef.Document != null);
          Debug.Assert(elements[idx].Document != null);
          if (elements[idx].ObjectID.ObjectNumber == 12)
            GetType();
        }
#endif
      // 1st loop. Replace all objects by their clones.
      PdfImportedObjectTable iot = new PdfImportedObjectTable(owner, externalObject.Owner);
      for (int idx = 0; idx < count; idx++)
      {
        PdfObject obj = elements[idx];
        PdfObject clone = obj.Clone();
        Debug.Assert(clone.Reference == null);
        clone.Document = owner;
        if (obj.Reference != null)
        {
          // Case: The cloned object was an indirect object.
          // add clone to new owner document
          owner.irefTable.Add(clone);
          // the clone gets an iref by adding it to its new owner
          Debug.Assert(clone.Reference != null);
          // save an association from old object identifier to new iref
          iot.Add(obj.ObjectID, clone.Reference);
        }
        else
        {
          // Case: The cloned object was an direct object.
          // only the root object can be a direct object
          Debug.Assert(idx == 0);
        }
        // replace external object by its clone
        elements[idx] = clone;
      }
#if DEBUG_
        for (int idx = 0; idx < count; idx++)
        {
          Debug.Assert(elements[idx].XRef != null);
          Debug.Assert(elements[idx].XRef.Document != null);
          Debug.Assert(resources[idx].Document != null);
          if (elements[idx].ObjectID.ObjectNumber == 12)
            GetType();
        }
#endif

      // 2nd loop. Fix up all indirect references that still refers to the import document.
      for (int idx = 0; idx < count; idx++)
      {
        PdfObject obj = elements[idx];
        Debug.Assert(obj.Owner == owner);
        FixUpObject(iot, owner, obj);
      }

      // return the clone of the former root object
      return elements[0];
    }

    ///// <summary>
    ///// Imports an object and its transitive closure to the specified document.
    ///// </summary>
    /// <param name="importedObjectTable">The imported object table of the owner for the external document.</param>
    /// <param name="owner">The document that ownes the cloned objects.</param>
    /// <param name="externalObject">The root object to be cloned.</param>
    /// <returns>The clone of the root object</returns>
    internal static PdfObject ImportClosure(PdfImportedObjectTable importedObjectTable, PdfDocument owner, PdfObject externalObject)
    {
      Debug.Assert(Object.ReferenceEquals(importedObjectTable.Owner, owner), "importedObjectTable does not belong to the owner.");
      Debug.Assert(Object.ReferenceEquals(importedObjectTable.ExternalDocument, externalObject.Owner),
        "The ExternalDocument of the importedObjectTable does not belong to the owner of object to be imported.");

      // Get transitive closure of external object
      PdfObject[] elements = externalObject.Owner.Internals.GetClosure(externalObject);
      int count = elements.Length;
#if DEBUG_
        for (int idx = 0; idx < count; idx++)
        {
          Debug.Assert(elements[idx].XRef != null);
          Debug.Assert(elements[idx].XRef.Document != null);
          Debug.Assert(elements[idx].Document != null);
          if (elements[idx].ObjectID.ObjectNumber == 12)
            GetType();
        }
#endif
      // 1st loop. Already imported objects are reused and new ones are cloned.
      for (int idx = 0; idx < count; idx++)
      {
        PdfObject obj = elements[idx];
        Debug.Assert(!Object.ReferenceEquals(obj.Owner, owner));

        if (importedObjectTable.Contains(obj.ObjectID))
        {
          // External object was already imported
          PdfReference iref = importedObjectTable[obj.ObjectID];
          Debug.Assert(iref != null);
          Debug.Assert(iref.Value != null);
          Debug.Assert(iref.Document == owner);
          // replace external object by the already cloned counterpart
          elements[idx] = iref.Value;
        }
        else
        {
          // External object was not imported ealier and must be cloned
          PdfObject clone = obj.Clone();
          Debug.Assert(clone.Reference == null);
          clone.Document = owner;
          if (obj.Reference != null)
          {
            // Case: The cloned object was an indirect object.
            // add clone to new owner document
            owner.irefTable.Add(clone);
            Debug.Assert(clone.Reference != null);
            // save an association from old object identifier to new iref
            importedObjectTable.Add(obj.ObjectID, clone.Reference);
          }
          else
          {
            // Case: The cloned object was a direct object.
            // only the root object can be a direct object
            Debug.Assert(idx == 0);
            //// add it to this (the importer) document
            //owner.irefTable.Add(clone);
            //Debug.Assert(clone.Reference != null);
          }
          // replace external object by its clone
          elements[idx] = clone;
        }
      }
#if DEBUG_
      for (int idx = 0; idx < count; idx++)
      {
        Debug.Assert(elements[idx].XRef != null);
        Debug.Assert(elements[idx].XRef.Document != null);
        Debug.Assert(elements[idx].Document != null);
        if (resources[idx].ObjectID.ObjectNumber == 12)
          GetType();
      }
#endif

      // 2nd loop. Fix up indirect references that still refers to the external document.
      for (int idx = 0; idx < count; idx++)
      {
        PdfObject obj = elements[idx];
        Debug.Assert(owner != null);
        FixUpObject(importedObjectTable, importedObjectTable.Owner, obj);
      }

      // return the imported root object
      return elements[0];
    }

    /// <summary>
    /// Replace all indirect references to external objects by their cloned counterparts
    /// owned by the importer document.
    /// </summary>
    internal static void FixUpObject(PdfImportedObjectTable iot, PdfDocument owner, PdfObject value)
    {
      Debug.Assert(Object.ReferenceEquals(iot.Owner, owner));

      PdfDictionary dict;
      PdfArray array;
      if ((dict = value as PdfDictionary) != null)
      {
        // Set document for cloned direct objects
        if (dict.Owner == null)
          dict.Document = owner;
        else
          Debug.Assert(dict.Owner == owner);

        // Search for indirect references in all keys
        PdfName[] names = dict.Elements.KeyNames;
        foreach (PdfName name in names)
        {
          PdfItem item = dict.Elements[name];
          // Is item an iref?
          PdfReference iref = item as PdfReference;
          if (iref != null)
          {
            // Does the iref already belongs to the owner?
            if (iref.Document == owner)
            {
              // Yes: fine. Happens when an already cloned object is reused.
              continue;
            }
            else
            {
              //Debug.Assert(iref.Document == iot.Document);
              // No: replace with iref of cloned object
              PdfReference newXRef = iot[iref.ObjectID];
              Debug.Assert(newXRef != null);
              Debug.Assert(newXRef.Document == owner);
              dict.Elements[name] = newXRef;
            }
          }
          else if (item is PdfObject)
          {
            // Fix up inner objects
            FixUpObject(iot, owner, (PdfObject)item);
          }
        }
      }
      else if ((array = value as PdfArray) != null)
      {
        // Set document for cloned direct objects
        if (array.Owner == null)
          array.Document = owner;
        else
          Debug.Assert(array.Owner == owner);

        // Search for indirect references in all array elements
        int count = array.Elements.Count;
        for (int idx = 0; idx < count; idx++)
        {
          PdfItem item = array.Elements[idx];
          // Is item an iref?
          PdfReference iref = item as PdfReference;
          if (iref != null)
          {
            // Does the iref already belongs to the owner?
            if (iref.Document == owner)
            {
              // Yes: fine. Happens when an already cloned object is reused.
              continue;
            }
            else
            {
              Debug.Assert(iref.Document == iot.ExternalDocument);
              // No: replace with iref of cloned object
              PdfReference newXRef = iot[iref.ObjectID];
              Debug.Assert(newXRef != null);
              Debug.Assert(newXRef.Document == owner);
              array.Elements[idx] = newXRef;
            }
          }
          else if (item is PdfObject)
          {
            // Fix up inner objects
            FixUpObject(iot, owner, (PdfObject)item);
          }
        }
      }
    }

    /// <summary>
    /// Gets the indirect reference of this object. If the value is null, this object is a direct object.
    /// </summary>
    public PdfReference Reference
    {
      get { return this.iref; }
      set
      {
        //Debug.Assert(value.Value == null);
        this.iref = value;
      }
    }
    internal PdfReference iref;
  }
}